ITU Stamps G.fast

G.fast, the technology that will bring 1-Gig speeds to DSL, reached a milestone Friday as the members of the ITU awarded final approval to the standard.

G.fast aims to upgrade the speed capabilities of DSL networks without the expense of deploying FTTP, but telcos won’t be able to take advantage of such speeds unless the loop lengths are relatively short.

But in those situations, G.fast will give telcos a way to hold off on FTTP upgrades and unlock more DSL capacity in a way that makes the technology more competitive with cable’s current DOCSIS 3.0 platform and the coming DOCSIS 3.1 platform, which is targeting multi-gigabit speeds. G.fast could also position DSL to support more bandwidth-intensive services and applications such as 4K streaming and WiFi backhaul.

Friday’s ITU approval is for the physical-layer protocol aspects of G.fast, and follows approval in April of a companion text specifying methods to ensure that G.fast equipment will not interfere with broadcast services such as FM radio. Work on an “extended set of features” for G.fast, including the inclusion of a range of low-power states, is underway.

The ITU noted that The Broadband Forum has begun developing a test suite and certification program for G.fast systems, with a beta trial anticipated by mid-2015. Certified G.fast implementations are expected to appear on the market before the end of 2015, the ITU said. The University of New Hampshire InterOperability Laboratory is the first testing lab on board for G.fast certification testing.

“The time from G.fast’s approval to its implementation looks set to be the fastest of any access technology in recent memory. A range of vendors has begun shipping G.fast silicon and equipment, and service providers’ lab and field trials are well underway,” said Dr.Hamadoun I. Touré, the ITU’s Secretary-General, in a statement.

Chipmakers are already developing G.fast products, with some expecting to reach volume production by mid-2015. Alcatel-Lucent and Adtran are among vendors that have been talking about upcoming G.fast trails with operators.

G.fast’s 1-Gig claim represents the aggregate data capacity (upstream plus downstream) it's gunning for. And while G.fast, which requires a noise-cancellation technology called vectoring (in use already by telcos such as KPN of the Netherlands, Swisscom, BT, Belgacom, Deutsche Telekom and AT&T), it's usable within 400 meters of a distribution point, though industry analysts hold that G.fast will need much shorter loop lengths to achieve a sizable data boost.

Given some of those limitations and questoins, analysts who track the broadband access market and are keeping tabs on G.fast aren’t ready to call it a home run. But they understand the value proposition.

“G.fast is going to have legs, but the question is how long are those legs going to be,” Teresa Mastrangelo, founder of marketing analysis and consulting firm Broadbandtrends, said in a recent interview with Multichannel News (subscription required). “The telcos are excited about the potential for G.fast and the speed that it can provide.”

At the time, Mastrangelo said operators will need loop lengths in the range of 25 meters to 40 meters to get the biggest bang out of G.fast, but notes that the initial trials are using more realistic loop lengths that enable speeds in the vicinity of 100 Megabits per second to 200 Mbps.